This invention relates to endless belt conveyors and more particularly to an improved roller for such a conveyor, especially in an agricultural machine application usig a flat belt combined with an integral V belt section.
Conveyors in which an endless flexible flat belt is trained around a series of cylindrical rollers, one or more of which is driven so as to drive the belt through friction between the belt and roller, are well known. As is also known, it is sometimes difficult to control the tracking of such belts which may not remain centered on the rollers, but run to one side or the other possibly damaging the belt and interfering with the function of the conveyor. This is particularly true with relatively short wide conveyors using belts of heavy construction which are typical of some agricultural machines such as large round balers.
In farm equipment applications, the machine environment frequently imposes limitations on the proportions of the conveyor, and the roller diameter may be small in relation to belt width. In such a conveyor there may be insufficient friction between roller and belt to drive the belt reliably and friction may be increased by a modification of the belt/roller system which includes the equivalent of a V belt section bonded to the inside of the belt engaging a V-shaped groove formed in the plain cylindrical roller. The conveyor thus becomes a "dual belt" system, a combination of V and flat with neither the V nor the flat dominant. The tracking of such a system is unpredictable and unreliable, particularly if the payloading of the belt is heavy, intermittent and nonuniform as is typical in agricultural crop material conveying.
The V belt in conjunction with the V-shaped groove has a strong guiding or tracking potential because of its well defined physical form. However, in the "dual belt" where the V section is combined with the flat, lateral forces developing in the flat portion of the belt, for example, due to misalignment of rollers or bias in the belt construction, or belt joint configuration, can so bias the V belt section sideways as to cause it to ride out of its groove. Even if belt roller adjustment is made regularly, paying meticulous attention to roller alignment and belt tension, these conveyors are still prone to work interruption and belt damage through mistracking, principally because of the tendency of the V belt section to ride out of its groove, especially on an idler roller, allowing the conveyor belt to run off track and afoul of other parts of the machine.